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Heterogeneous Structure Design to Strengthen Carbon-Containing CoCrFeNi High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1503-1510页

作者： Xiaomeng Qin Chan Hung shek Department of Materials Science and Engineering City University of Hong KongKowloonHong Kong SAR 999077China

A carbon-containing CoCrFeNi high entropy alloy(HEA)with heterogeneous structures was obtained through thermomechanical treatments,which induced concurrent recrystallization and carbide precipitation in the alloy.A combination of high yield strength(556 MPa)and large uniform elongation(45%)was achieved in the investigated *** enhancement of the strength is attributed to the combined effects of grain refinement,precipitation strengthening and microstructural *** work demonstrated that the heterogeneity design could be realized by thermomechanical processes,which provided a practical strategy for producing HEAs with high performance.

关键词： High entropy alloy Heterogeneous structures Mechanical properties Interstitial

Machine learning prediction of magnetic properties of Fe-based metallic glasses considering glass forming ability

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Journal of Materials Science & Technology 2022年第8期103卷 113-120页

作者： Xin Li Guangcun Shan C.H.shek School of Instrumentation Science and Opto-electronics Engineering Beihang UniversityBeijing 100191China Department of Materials Science and Engineering City University of Hong KongKowloon TongHong Kong SARChina

Fe-based metallic glasses(MGs)have shown great commercial values due to their excellent soft magnetic *** prediction with consideration of glass forming ability(GFA)is of great signifi-cance for developing novel functional Fe-based ***,theories or models established based on condensed matter physics exhibit limited accuracy and some *** this work,based on 618 Fe-based MGs samples collected from published works,machine learning(ML)models were well trained to predict saturated magnetization(B_(s))of Fe-based *** was treated as a feature using the experimental data of the supercooled liquid region(△T_(x)).Three ML algorithms,namely eXtreme gradient boosting(XGBoost),artificial neural networks(ANN)and random forest(RF),were *** feature selection and hyperparameter tuning,XGBoost showed the best predictive performance on the randomly split test dataset with determination coefficient(R^(2))of 0.942,mean absolute percent error(MAPE)of 5.563%,and root mean squared error(RMSE)of 0.078 T.A variety of feature importance rankings derived by XGBoost models showed that T_(x) played an important role in the predictive performance of the *** work showed the proposed ML method can simultaneously aggregate GFA and other features in ther-modynamics,kinetics and structures to predict the magnetic properties of Fe-based MGs with excellent accuracy.

关键词： Metallic glasses Soft magnetic properties Glass forming ability Machine learning Non-linear regression

Left atrial dimension and atrial fibrillation in surgical heart disease patients

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Journal of Geriatric Cardiology 2008年第1期5卷 11-14页

作者： David shek Division of Cardiology Hospital of University of Pennsylvania

Objective The effect of left atrial (LA) dimension on the occurrence of atrial fibrillation (AF) has been examined in some small *** is known about the relationship of LA dimension,hemodynamic with AF during echocardiographic evaluation,especially,the flow dynamics in LA poorly *** objective of this study was to investigate the relationship between LA dimension and the occurrence of AE Methods Two hundred and forty-five consecutive patients with heart disease scheduled to undergo open heart surgery were prospectively enrolled in the *** were divided into 2 groups according to atrial fibrillation:AF group (n=148,99 men and 49 women,with a mean age 59.3+8.4 years),and no-AF group (n= 97,60 men and 37 womem).Echocardiography was performed before *** measurements were performed following the American Society of Echocardiography *** There were more patients with congestive heart failure in AF group than in no-AF group (45.9% vs 39.1%,P ＜0.05).The mean LA volume was 49.2±12.2 ml/m2 in AF group and 33.1±10.8 ml/m2 in no-AF *** were also significant differences between two groups in left atrial end systolic dimension (LAESD) (50±13mm vs 27±14mm),left atrial end diastolic dimension (LAEDD) (79±17mm vs 53±13mm),PA pressure ( 41.3+11.6 mmHg vs 37.5±10.4 mmHg),and ratio of mitral E velocity and septal mitral annulus motion velocity (E/E') .The percentage of abnormal diastolic function grades (DGF) was also higher in AF than in no-AF group (89.9% versus 59.8% );.Conclusion Atrial fibrillation is associated more frequently with an increased LA dimension and more severe atrial hemodynamics disorder.(J Geriatr Cardiol 2008;5:11-4)

关键词： LA dimension hemodynamics atrial fibrillation

Promoting International Students’Mental Health Unmet Needs:An Integrative Review

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International Journal of Mental Health Promotion 2024年第11期26卷 905-924页

作者： Carmen Hei Man shek Sally Wai chi Chan Michelle Anne Stubbs Regina Lai Tong Lee School of Nursing and Midwifery College of HealthMedicine and WellbeingUniversity of NewcastleCallaghanNSW 2308Australia President’s Office Tung Wah CollegeHong KongChina The Nethersole School of Nursing The Chinese University of Hong KongShatinNew TerritoriesHong KongChina

Background:There are increasing concerns about the mental health needs of international *** studies report that international students experience additional challenges and higher levels of stress compared to domestic *** integrative review aimed to identify perceived stressors,coping strategies and factors that contributed to accessing mental health services of international ***:A systematic search was performed between January 2010 and December 2023 using PubMed,CINAHL,ProQuest,the Cochrane Library,Scopus and PsycINFO databases.A manual search was also performed that included reference lists of included articles;data was extracted and reviewed by three reviewers.A total of 21 studies were included in this review with a total of 4442 international students recruited,with ages between 17 to 43 *** studies reported international students’gender,there were more females(n=2205)than males(n=1022).Ethnicity was reported in 18 *** included Asia,Europe,Latin America,North America,South America,Africa,the Middle East and Pacific *** review adopted Whittemore and Knafl’s five-stage approach,with specific steps for problem identification,literature search,data evaluation,data analysis,and ***:The Health Belief Model was used to explain relationships among independent and dependent variables and guide the findings of this *** identified progressive themes emerged including Theme 1:understanding cultural variations with perceived stress;Theme 2:coping strategies in dealing with stress and challenges in the new environment;and Theme 3:perceived threats and stress affecting how international students perceived barriers and benefits to access counselling support services and mental health *** integrative review presents an overview of mental health needs and factors contributing to the mental health and well-being of international students via the inclusion of studies with differen

关键词： International students challenges coping mental health needs

Development of Dual Phosphorescent Materials Based on Multiple Stimuli-Responsive Ir(Ⅲ)Acyclic Carbene Complexes

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CCS Chemistry 2022年第7期4卷 2354-2368页

作者： Jingqi Han Yuen-Kiu Chun Shing-Lun Chan Shun-Cheung Cheng shek-Man Yiu chi-chiu Ko Department of Chemistry City University of Hong KongKowloonHong Kong 999077

A new series of Ir(Ⅲ)carbene complexes with luminescent mechanochromism derived from trans-cis isomerization has been *** the introduction of π-conjugating groups into the acyclic carbene ligand,the mechanochromic trans-and cisconfigurations can be readily interconverted,leading to dual emissive properties in the solid ***,the solid-or film-forming solvent system can control the dual emission and mechanoresponsive properties in the solid *** potential uses of a single emissive complex to develop multicolor emissive and multiple stimuli-responsive films have been studied.

关键词： luminescent mechanochromism iridium(Ⅲ)cyclometallates luminescent vapochromism dual emission

Effect of Electropulsing on Recrystallization and Mechanical Properties of Silicon Steel Strips

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Journal of Materials Science & Technology 2011年第11期27卷 1034-1038页

作者： Guoliang Hu Yaohua Zhu Guoyi Tang Chanhung shek Iianan Liu Materials Department and Advanced Materials Institute Tsinghua University Shenzhen 518055 China Department of Industrial and Systems Engineering Hong Kong Polytechnic University Kowloon Hong Kong China Department of Physics and Materials Science City University of Hong Kong 83 Tat Chee Avenue Kowloon Tong Honk Kong China

Electropulsing-induced recrystallization and its effect on mechanical properties of oriented silicon steel strips （Fe-3.0%Si） were studied by optical microscopy, scanning electron microscopy and electron back-scatter diffraction. The results indicated that electropulsing accelerated recrystallization, and decreased the temperature of recrystallization. Electropulsing favors refinement of the grain structure of the alloy. Effects of electropulsing on strength and elongation of the alloy were discussed from the point view of dislocation dynamics, microstructural changes, and electropulsing kinetics.

关键词： Recrystallization Electropulsing Oriented silicon steel strip

The role of gene variants in the pathogenesis of neurodegenerative disorders as revealed by next generation sequencing studies:a review

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Translational Neurodegeneration 2017年第1期6卷 245-255页

作者： Shirley Yin-Yu Pang Kay-Cheong Teo Jacob Shujui Hsu Richard shek-Kwan Chang Miaoxin Li Pak-chung Sham Shu-Leong Ho Division of Neurology Department of MedicineQueen Mary HospitalUniversity of Hong KongHong KongPeople’s Republic of China Centre for Genomic Sciences University of Hong KongHong KongPeople’s Republic of China Department of Medical Genetics Zhongshan School of MedicineSun Yat-sen UniversityGuangzhouPeople’s Republic of China Key Laboratory of Tropical Disease Control(SYSU) Ministry of EducationGuangzhouPeople’s Republic of China

The clinical diagnosis of neurodegenerative disorders based on phenotype is difficult in heterogeneous conditions with overlapping *** does not take into account the disease etiology or the highly variable clinical course even amongst patients diagnosed with the same *** advent of next generation sequencing(NGS)has allowed for a system-wide,unbiased approach to identify all gene variants in the genome *** the plethora of new genes being identified,genetic rather than phenotype-based classification of Mendelian diseases such as spinocerebellar ataxia(SCA),hereditary spastic paraplegia(HSP)and Charcot-Marie-Tooth disease(CMT)has become widely *** has also become clear that gene variants play a role in common and predominantly sporadic neurodegenerative diseases such as Parkinson’s disease(PD)and amyotrophic lateral sclerosis(ALS).The observation of pleiotropy has emerged,with mutations in the same gene giving rise to diverse phenotypes,which further increases the complexity of phenotype-genotype *** mechanisms of pleiotropy include different downstream effects of different mutations in the same gene,presence of modifier genes,and oligogenic *** directions include development of bioinformatics tools and establishment of more extensive public genotype/phenotype databases to better distinguish deleterious gene variants from benign polymorphisms,translation of genetic findings into pathogenic mechanisms through in-vitro and in-vivo studies,and ultimately finding disease-modifying therapies for neurodegenerative disorders.

关键词： Next generation sequencing Neurodegenerative diseases Genetics Pleiotropy

Protective Effect of Liposomal α-Tocopherol Against Bleomycin-induced Lung Injury

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Biomedical and Environmental Sciences 1997年第1期10卷 47-59页

作者： Z·E·SUNTRES P·N·shek OperationalMedicineSector DefenceandCivilInstituteofEnviron－mentalMedicineNorthYork Towhomcorreponde

The clinical use of bleomycin in the treatment of squamous cell carcinomas, lymphomas and testicular tumours has been limited by its toxic effects, the most serious being pulmonary injury. The present study was undertaken to invesigate whether α-tocopherol, incorprated in liposomes and delivered directly to the lung, could offer protection against bleomycin-induced lung damage and fibrosis in the rat. Animals were administered, intratracheally, plain lipo somes (composed of dipalmitoylphosphatidylcholine, DPPC ) or α- tocopherol-containing lipo somes (8 mg Q-tocopherol/kg body weight) and 30 min later, were exposed to bleomycin sul phate (4 units/kg body weight) by intratracheal instillation; treated animals were killed 21 days later. Results of this study showed that lungs of animals treated with bleomycin were se riously damaged, as evidenced by significant histological changes and increases in lung weight,lipid peroxidation, myeloperoxidase activity and hydroxyproline content as well as decreases in lung angiotensin converting enzyme (ACE) and alkaline phosphatase (AKP) activities. Pre treatment of rats with plain liposomes alone did not alter significantly the bleomycin-induced changes of all parameters examined. In contrast, pretreatment of rats with α-tocopherol lipo somes 30 min prior to bleomycin administration resulted in little or no histological changes and conferred a significant protection against bleomycin-induced changes in edema, lipid peroxida tion, hydroxyproline content, and ACE, AKP and myeloperoxidase activities. Results of this study suggested that pretreatment of rats with α-tocopherol liposomes can provide a significant protection against bleomycin-induced lung injury

关键词： lung Protective Effect of Liposomal Tocopherol Against Bleomycin-induced Lung Injury

Single photon sources with single semiconductor quantum dots

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Frontiers of physics 2014年第2期9卷 170-193页

作者： Guang-Cun Shant Zhang-Qi Yin Chan Hung shek Wei Huang Department of Physics and Materials Science City University of Hong Kong Hong Kong SAR China The Fu Foundation School of Engineering and Applied Science Columbia University New York NY 10027 USA The Institute for Interdisciplinary Information Sciences (IHS) Tsinghua University Beijing 100084 China Singapore-Jiangsu Joint Research Center for Organic/Bio-electronics and Information Displays and Institute of Advanced Materials Nanjing University of Technology Nanjing 211816 China

In *** contribution, we briefly recall the basic concepts of quantum optics and properties of semicon- ductor quantum clot. （QD） which *** necessary to the nnderstanding of the physics of single-photon generation with single QDs. Firstly, we address the theory of quantmn emitter-cavity system, the fluorescence and optical properties of semiconductor QDs, and the photon statistics as well as opti- cal properties of the QDs. We then review the localizatioll of single semiconductor QDs in quantum confined optical microcavity systems to achieve their overall optical properties and perfornances in terms of strong coupling regime, elfieiency, directionality, and polarization control. Furthermore, we will discuss the recenl, progress on the fabrication of single photon sources, and various *** for embedding single QDs into mieroca,vities or photonic crystal nanoeavities and show how to ex- tend the wavelength range. We focus in part;icular on new generations of electrically driven QD single photon source leading to high repetition rates, efficiencies at elevated temperature operation. Besides strong eoupling regime, and high collection new development;s of room temperature sin- gle photon emission in the strong coupling regime are reviewed. The generation of indistinguishable photons and remaining challenges for pract ical single-photon sources are also discussed.

关键词： single-photon source quantum dot (QD) quantum optics photon correlation